1. Field of the Invention
The invention relates to a communication control method, a communication control apparatus, a communication control program and a recording medium for performing communication flow control by combining a software unit that controls communication flow.
2. Description of Related Art
As examples of a method for performing communication flow control by combining a software unit that controls communication flow, there are streams/XTI, and an active protocol stack method represented by Filter Streams function in Java (Trademark) language. See, for example, AT&T, Unix System V Release 4: Programmer's Guide: Streams, June 1992, ISBN 0130206601; NTT public release “Feb. 27, 2002”; Internet <http://www.ntt.co.jp/news/news02/0202/020227.html>; Tsutsui, “Advanced network utilization technique study project N*Vector”, NTT R&D, Vol. 51, No. 2, pp. 76-85, 2002; and Kakinuma and Fujii, “Next generation home network technique”, NTT technical journal, Vol. 14, No. 1, pp. 51-55, 2002.
According to the prior methods, the protocols and software units, which execute communication signal processing representative of a signal filter, are selectively combined. A communication signal sent out from an application is sequentially transferred to the software units, which controls the communication flow.
In the active protocol stack method of the prior art, since the software units for performing communication control are constructed only in a communication terminal, there is a problem that communication control can be performed only in the terminals. Because of this, for example, there is a problem that communication control for a mobile terminal having a low calculation capability cannot be carried out in a network device. In addition, there is a problem that software units cannot be constructed which are based on congestion information known only in a network.
Since the structure of software units is carried out only at the time when an application is activated and then cannot be changed during operation of the application, there is a problem that communication control cannot be actively altered depending on a change in a network or communication state or a request of a user.
A constituent software unit is limited to the one that is present beforehand in a communication terminal. Accordingly, there is a problem that software units, which may be possibly used, have to be owned all the time. When a new software unit appears, or software unit already available is changed, there is a problem that the software units should be installed for their use in the communication terminals by using some sorts of means.
Because it is not assumed that software units are developed by many unspecified developers, there is a problem that no function is existent for identifying who prepared a specified software unit and for verifying whether, after the preparation, a modification of the software unit has been made.